EXTRACTION OF COBALT (II) IN THE PRESENCE OF RHODANIDE IONS AND DIMETHYLFORMAMIDE AND COMPLEXATION WITH 1-(2-PYRIDYLAZO)-2-NAPHTHOLH IN THE ORGANIC PHASE
Journal Title: International scientific journal Science and Innovation - Year 2024, Vol 3, Issue 2
Abstract
Low selectivity for the determination of metal ions using azo dyes, as well as when using other organic reagents, during complex formation in the aqueous phase is the main disadvantage of existing methods. We have studied the conditions for selective extraction of the thiocyanate complex cobalt (II) in the presence of thiocyanate dimethylformamide (DMF) with inert organic solvents and its determination with 1-(2-pyridylazo)-2-naphthol (PAN) directly in the organic phase without separating accompanying elements. Experiments have shown that cobalt (II) from a strongly acidic medium in the presence of thiocyanate ions and DMF is selectively extracted with chloroform at 10-15 sec. shaking the cobalt (II) phases by 99.9% without changing to a phase volume ratio of 40:1. After extraction of cobalt (II) under optimal conditions, add to the extract the PAN reagent, a buffer solution pH = 3-5.5 containing 0.2% sodium nitrite and shaking the phases for 10-15 seconds. Interacting with a 1:2 ratio, a colored complex compound is formed. The rhodanide complex of cobalt (III) in the extract is stable for more than 3 days. The maximum absorption spectrum of cobalt with PAN is at 640 nm. The apparent molar absorption coefficient at 640 nm is 2∙〖10〗^4, obeying Beer’s law over a wide concentration range. Under optimal conditions, together with cobalt (II), ions of copper, iron (III), bismuth (III), tungsten (VI) are partially extracted and interfere with the determination of cobalt (III) with PAN. The interfering influences of iron (III) and bismuth (III) are eliminated by adding sodium fluoride and thiourea, copper (II) and tungsten (VI) to the buffer solution by adding thiourea and tartaric acid, respectively. It has been established that the thiocyanate complex of cobalt (II) is selectively extracted from a strongly acidic medium in the presence of DMF by the hydrate-solvate mechanism. The developed method for the extraction-spectrophotometric determination of cobalt with PAN was tested in model solutions composed according to the type of rocks and ores, as well as salts and ores, and is recommended for the analysis of ores, concentrates, steel and other materials with complex compositions without preliminary separation of associated elements.
Authors and Affiliations
A. Sh. Giyasov, Rakhmatullaeva N. T, A. A. Shokhakimova, Rakhmatov U. N, Otayuziea V. U
Keywords
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- EP ID EP731915
- DOI 10.5281/zenodo.10726019
- Views 57
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